Term
| What role do carbon sequestration, albedo and evapotranspiration play in regulating climate? |
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Definition
Albedo = Reflectivity
higher albedo more sw reflected back into space
leads to cooler climate
decrease albedo, take in more energy and increasing average temperature.
ET-increases water vapor in air (GHG) when evap cooling occurs, decreases temperature.
think sweating or hiking in forest |
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Term
| Be able to discuss each of the 3 factors above with respect to regulating climate between tropical forests and the atmosphere. Which is most important? Would you recommend afforestation in the tropics and why? |
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Definition
carbon sequestration: undisturbed, intact tropical forest have large C sequestration potential
Majority of C stored in above ground biomass (1/3 land surface)
Peatlands also store C below ground
undisturbed=C sink disturbed=C source
Albedo
intact-low albedo
disturbed-high albedo, reflects SW radiation
influences ITCZ when vegetative have high ET, add moisture, creates cloud cover
Evapotranspiration-1/3 global ET occurs in tropics, largest GPP, intact forest have high ET rates which cools surface and creates more wet/humid environment-perpetuates ITCZ trends
Most important is sequestration
tropical forest considered tipping element because majority is stored in above ground biomass
reforestation-probably good idea because water is not limiting. A long time for forest to grow so afforestation is best |
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Term
| Be able to write out the equation to define Net Ecosystem Production and Net Biome Production, and be able to explain it in words. Make sure you know the units involved in each of the terms and what a negative sign vs positive sign means. |
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Definition
units: Gt C / yr (both)
Net Primary Production (NPP) → short-term carbon storage (how much plant biomass is gained over a time period)
Net ecosystem production (NEP) → medium-term carbon uptake (how much carbon is taken up by the ecosystem)
Net Biome Production (NBP) → long-term carbon storage
Heterotrophic respiration (Rhet) → Plant respiration is ~60Gt C / yr
NEP = NPP - Rhet = Change in biomass → balance between two large fluxes
NBP = NEP - disturbances? → takes into account losses of carbon from ecosystems due to disturbances like fires, insect outbreaks, harvests, that can’t be accounted for in the NEP |
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Term
| Why is measuring tower-based eddy covariance over a biome the equivalent of repeated measures of carbon pool in the biome? |
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Definition
| Measures fluxes of carbon exchange (CO2, photosynthesis, respiration (from plants), respiration (from microbes)). Its a continuous measurement that occurs day and night, so we have data every x amount of time (hence the repeated measures). These towers can only be put on flat land. |
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Term
| Be ready to interpret and explain variability in seasonal patterns of NEP between biomes. |
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Definition
NEP= GPP-Respiration
Think of the bathtub example where NEP is the change between incoming photosynthesis and outgoing respiration.
NEP varies between biomes due to latitude, growing season, and land mass. It is regulated by light, temperature, herbivory, water, and nutrients.
Phenology plays a role in variability, growing season in the East (US) can sequester more carbon than the West (US).
Biomes with higher photosynthetic rates sequester more carbon. Remember to note how much land a biome occupies (tropical forests vs boreal forests, tropics are more efficient and have more land so they take in more carbon because both of those)
Disturbed biomes lose more carbon.
There is interannual variability between carbon sink strength across all biomes. |
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Term
Using slides 44 -46 from lecture 15, be able to relate the increase in NPP from 1982 to 1999 to climatic changes during this period. Which latitudes and/or biomes in particular responded the most in terms of increased NPP?
* |
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Definition
| Increased NPP in this time seemed most related to increases in growing season temperatures as well as greater solar radiation, which must have been partially related to reduced cloud/aerosol cover over the tropics. These areas are usually restrained in productivity because it rains too much and reduces solar radiation availability. With that removed, these areas were able to take in more CO2 and produce the patterns seen in the equatorial regions of the planet. The higher latitudes seemed to also have more precipitation during this period, which caused more productivity since most other areas of the world are water limited (relative to radiation) and could grow more with more water. |
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Term
Which graphs from this lecture showed the very tight relationship between NPP and CO2 growth rate in the atmosphere – and be ready to explain them.
* |
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Definition
CO2 fertilization alone does not explain the trends
2000-2009:
Global NPP decreased by .55 Pg C over this decade
NPP in tropics explains 93% variation in global NPP - 66% due to Amazon alone
El nino event = drought in the tropics
“Amazingly tight relationship between NPP and atmospheric CO2 growth rate!” - Marcy Litvak
NPP negative anomalies were mainly caused by droughts
NPP controlled by: 1) Temperature, 2) Vapor Pressure Deficit, and 3) Solar radiation, increased temperature influences land cover in the Northern Hemisphere and Southern Hemisphere differently |
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Term
From the Williams et al. paper and what Craig Allen discussed in class– what is the Forest Drought Severity Index? What were the two most important climate variables that were used to calculate this? How much of the variability in tree growth was explained by each climate variable individually, and then both together? Which variable was more important? What does that tell you about climate changes in the future that will be most important in driving mortality?
*** |
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Definition
The forest drought-stress index (FDSI) is an index they calculate from the tree rings, which indicates the water stress caused by vapour-pressure deficit (VPD) and precipitation. (they link this index to regional forest productivity and disturbance records).
The warm-season VPD has been particularly high since 2000 and is the primary driver of an ongoing drought-stress event. (and precipitation)
Before, precipitation was causing the drought, but because temperature is increasing more and more in the South West (hotter and drier), it is now temperature that is driving tree mortality.
The warm-season VPD is largely driven by the maximum daily temperature (Tmax) in the SW US. As such, warm-season Tmax is nearly as effective as the warm-season VPD at predicting the FDSI.
The strong correspondence between forest drought-stress and tree mortality suggests that intensified drought-stress will be accompanied by increased forest decline. |
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Term
| What are the three important physiological/ecological mechanisms that could explain how and why increased or drought has led to increased mortality in the SW US? Be able to list them but also write a few sentences about each one. |
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Definition
Cavitation from drought
Carbon starvation
Hotter and drier drought |
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Term
| How and why has fire frequency/severity changed in the SW in recent decades? Use specific examples from Craig’s discussion of Las Conchas fire vs fire in the Valles Caldera over the past couple centuries. |
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Definition
Fires have increased in severity and frequency over the last few decades. Increases in drought and heat cause stress of fires to be more severe than in the past. There are implications for a change in the hydrology regimes as you burn the “sponge” on the forest floor, losing moisture, exposing trees to drought stress, and increased risk of fire.
Losing large trees will be a huge problem in the future, increased forest density will increase the severity and frequency
Las Conchas-severe because of fire weather conditions, lack of precipitation, hot and dry weather, caused fire to spread at a fast rate. Lost almost all of overstory tree cover for miles, this is different from historic regimes at low severity in the understory. This caused seed abundance to decrease because the canopy and overstory was torched.
Valles Caldera Fire- low severity, frequently occurring, clearing litter, relatively small and did not spread far because of the frequent fire patches |
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Term
| Which trees appear to be the most vulnerable to changes in climate? |
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Definition
Large, old trees are the most vulnerable because they are have the highest susceptibility to changes because they are well established to the environment that they are growing in. Specifically, they are usually more targeted by infestations and have a hard time moving water up to the highest parts of the tree, so are more prone to cavitation and dying from water stress.
Old trees behave differently ecologically. |
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Term
| Why specifically are the arctic/boreal forest biomes so important to the global carbon cycle and climate system? |
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Definition
| arctic/Boreal biomes are considered to be a “tipping element” in the climate system because of their importance to the global carbon cycle. In both biomes, a large amount of carbon is stored (glacial dust) primarily in the soils -- conservative estimate is ~1672 Pg C. In boreal forests most carbon is stored belowground and the vegetation never fully decomposes causing thick layers of peat and permafrost to form. Due to the large carbon storage, it’s important to understand how these biomes will respond to climate change. As temperatures rise, the amount of CO2 and CH4 that could potentially be released would be a tipping point in the C cycle that we would not be able to recover from in our lifetime. |
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Term
| What is the definition of permafrost, and active layer and why are both so important to think about in a climate change context? In other words, how do they change as temperature increases and why? What processes are triggered by an increase in temperature that are important for climate? |
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Definition
Permafrost: soil that remains at or below the freezing point of water 0 °C for two or more years.
Active layer: A layer over permafrost that freezes and thaws annually.
If temperatures increase:
permafrost thaws, it will decompose quickly due to accelerated microbial decomposition of organic matter.
It will move C from frozen to thawed state rapidly and will increase the C pool size available for decomposition
Thickening of active layer –layer that is thawed in summer/frozen in winter –
Creation of taliks–a residual unfrozen soil layer with above freezing conditions --favorable for decomposition
Development of thermokarst–ground ice melts and surface soil collapses; new wetlands and lakes emerge
Eroded gullies form
Habitats change and infrastructure problems arise |
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Term
| Relate the total amount of carbon in permafrost and arctic soils to atmospheric CO2. If all of this gets converted to atmospheric CO2, is this a problem and why? |
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Definition
| A conservative estimate of carbon storage in arctic and boreal forests is ~1672 Pg C vs current atm CO2 levels are 400 ppm, so the release would change the arctic from a carbon sink to a carbon source. BAAAAD. Positive feedback loop where more C released causes warmer temperatures which causes more soil to thaw which releases more C and the cycle accelerates |
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Term
| Why specifically is there a concern that methane fluxes will increase with permafrost degradation? Where is the methane currently? Why would it’s release increase with climate change? |
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Definition
Permafrost carbon feedback: With increased warming, permafrost will melt, exposing more CO2 and methane, which will cause more warming, which will melt more permafrost, exposing more methane and CO2.
This is because there is methane within and below the permafrost under global contenental (and ocean) margins. Methane hydrate solid compounds are formed at high pressure and cold temperatures and get trapped under the crystallized water. The source is from microbes that break down available CO2 pools and make methane available under permafrost. |
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Term
| If permafrost melts, does that trigger a positive or negative climate feedback? Why specifically, draw out and be able to explain the feedback. |
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Definition
| Permafrost melting triggers a positive climate feedback because it unlocks lots of organic material that microbes and detritivores can break down, releasing CO2 and methane into the atmosphere, which in turn increases warming to melt more permafrost. It also increases the risks of fires occurring, which also release a lot of GHGs and cause further melting underneath. |
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Term
| What are 4 signs of increased warming in the Arctic over the past few decades? |
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Definition
First off, good to remember that warming is occurring 2x faster in the Arctic than anywhere else on Earth NEAT
Warming - air temperatures and ocean surface temperatures
2018 was especially crazy… sea surface was 14.7 degrees C warmer than average, 2019 was no different
Sea ice loss (thinner and smaller) - sea ice shrinking at a rate of 13.2% per decade
Melting land ice and sea level rise
Permafrost temps increasing, growing season length increasing |
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Term
What are 3 ecosystem scale changes that could lead to increased carbon uptake due to longer growing season in the arctic?
*** |
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Definition
1) Fire in very north north forests, cause a reduction in Carbon pools → longer growing season that’s warmer causes plants to lose mas agua creating fire prone conditions in an area that is not fire friendly
2) Insect disturbance stresses trees as their ranges expand with growing season, causing trees to die or stress causing less co2 uptake b/c danger
3) Phenology?Mismatches allow for decreased carbon uptake |
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Term
| What are the hypotheses we talked about in class driving shrubification? Be able to explain at least 3 of them |
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Definition
Shrubs are disproportionately favored as warming occurs.
Increased length in growing season favors slower growing shrubs.
Nutrient increases as more decomposition occurs from warmer climate, changes the cycling of nutrients
Increases in overall temperature are more favorable to shrubs than historic vegetation
Shrubs are taller, have deeper roots, and more ability for storage making them competition with grasses lacking these traits
Herbivory-ungulates prefer not to eat shrubs
Shrubs have a darker leaf area and can absorb more light compared to historic vegetation |
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Term
| What are the consequences of shrubification in the arctic for energy balance? |
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Definition
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Term
| What are the consequences of shrubification in the arctic for energy balance? |
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Definition
| They cause changes in energy exchange and ecosystem balance. For one, they outcompete grasses for resources, changing many areas from tundra grasslands to shrublands to the detriment of wildlife (not as energy rich and have anti-browsing toxins). It also increases energy capture and sensible heating that leads to more snowmelt and greater areas for more shrub encroachment. Am I missing anything? Changes in litter structure, many leaves vs grass creating diff microclimates |
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Term
| What are expected positive and negative consequences of shrubification in the arctic for higher trophic levels? Use caribou paper as an example. **** |
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Definition
energy exchanges-higher sensible heat flux
reflectance-lower albedo
snow melt-faster snow melt in areas with shrub canopies extended above snow pack
soil temp-snow trapping and soil warming in winter, shading and soil cooling in summer under shrub canopies relative to tundra plots
n cycling-greater n availability in tall shrubs
Impacts from caribou paper:
Increased shrubification led to decreased pasture quality, greening was mainly due to birch and alder which have anti-browsing toxins (that responded to warming temps) that proved to be very detrimental for caribou (respond to light day length). Also, shrub expansion decreases lichen abundance which is an important winter forage for caribou. |
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Term
| Compare/contrast fire in the boreal forest vs. the arctic tundra in terms of frequency and carbon dynamics. |
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Definition
Boreal forests survive/thrive in semi-regular high intensity fires, these ecosystems are used to more regular fires and will sequester C easier through regeneration after a fire.
Boreal forests survive/thrive in semi-regular high intensity fires, these ecosystems are used to more regular fires and will sequester C easier through regeneration after a fire.
Fires are unprecedented in (some parts) of the Arctic ecosystems and they will not sequester C easily when disturbed (not easy regeneration)... “Arctic tundra landscapes store large pools of C in organic-rich surface soil horizons that have accumulated over millennia and peatland organic soils, can be highly flammable when dry and may burn deeply” |
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Term
| If the frequency of fire increases the boreal forest how do you think this will affect the global carbon cycle? |
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Definition
Fire can change succession of incoming vegetation, increase GPP after burning event, increase respiration after burning event, and turn a tundra system into a sink after a burn event.
Carbon sequestration overall can be lost, there are large flammable pools of carbon in the soil surface accumulated over a long period of time and may burn deeply in the event of fire. |
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Term
| Is increased fire frequency more of a concern in one biome vs. the other? Why or why not? |
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Definition
| Increased fire frequency is more of a concern in the arctic than in the boreal forest because the arctic has more soil carbon stored in this region than the boreal (look at figure on pdf pg 5 and 6 and 57-59) and do not have species adapted to fire like boreal forests are. This mean that carbon lost from this system is not going to be re-sequestered within the next centuries and cannot grow trees that could represent a carbon sink like the boreal forests do. |
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Term
| Be able to discuss 1 positive feedback, AND 1 negative feedback to climate driven by warming in the arctic. |
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Definition
Positive feedbacks:
Loss/shrinking of sea ice results → more dark water exposed = An overall decrease in albedo, as the dark water absorbs more shortwave radiation and heats, causing ice to shrink more and the positive cycle continues
Same story with land ice… land ice melts, exposing dark ground underneath which results in a decrease in albedo/warmer temps which accelerates more melting
Permafrost thawing releases CO2 and CH4 → increases GHG in atmosphere → warms temperatures → accelerates permafrost thawing (irreversible, emissions would be released for centuries)
Fires in northern northern slope → peatland soils can be highly flammable and dry and burn deeply → severe decrease in C pools → release of CO2 to atmosphere → warmer temps, more fire prone, etc.
Early snowmelt → decrease in albedo
Decomposition → increase in CO2 release
Shrub growth → increase in sensible heat
Thermokarst → increase in CH4 release
Fire → increase in CO2 release
Treeline advance → decrease in albedo
Negative feedbacks:
Fire succession can be a stabilizing force (though not in the very northern areas).
Manitoba Case Study: 200 year fire interval
At first with the burn, it releases CO2 and becomes a carbon source, but over the successional regrowth period it becomes a sink as vegetation regrows. The sink period is longer than the source period, making this a negative feedback as the regrowth successional period sequesters more carbon than was lost.
Increase in NPP in response to N min
Fire-veg change → increase in albedo, decrease in sensible heat
Treeline advance → increase in NPP
shrubs- co2 uptake |
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Term
| Explain three reasons why the tropics are considered extremely crucial to understanding the global carbon cycle and global climate? |
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Definition
Store huge amounts of C (above ground biomass - AGB)
Huge spatial area covered
Lots of land use change/management going on, slow to regrow a forest |
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Term
| Is the tropical forest currently considered a source or a sink (Baccini et al. paper). How does this vary from the thinking on this a decade ago? |
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Definition
| according to Baccini et al., tropics are an overall source because of human and natural disturbances. They use NASA MODIS data with higher resolution satellite images (not everyone agrees because they only looked at woody plants). Other authors (a decade ago) it was considered a net source, because clearing and burning compensate for regrowth looking from a bottom-up ecological. |
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Term
| How specifically do both deforestation and tropical forest peat degradation alter the carbon budget of tropical forests? Use the examples we talked about in class to be able to discuss individual components and overall carbon balance. |
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Definition
Deforestation means less C absorbed by photosynthesis, less C stored above ground, less C stored in below ground biomass and increased emission from decay of slash-and-burn and soil erosion along with respiration.
Peat degradation from forest removal means that surface peat is oxidized and loses C to atmosphere. Peat is being converted to palm oil.
Lots of this land is being drained and converted to farmland. Once it is drained it decreases the anoxic layer. Oxygen layer increases increases so microbes can respire. |
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Term
| Be able to discuss examples we talked about in class with respect to influence deforestation has on local climate (via changes in energy balance). |
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Definition
| Reduced vegetation causes less moisture to be circulated back into the atmosphere via transpiration, which leads to warmer ambient temperature and less atmospheric moisture to come down on the forest there as well as other places north and south of the tropics (because of Hadley cell cycles). Fewer clouds means less reflectivity in the area as well. Drought is these areas also cause significant decreases in carbon uptake, which has implications for the forest transpiration (cooling) rates and global carbon cycling. The dieoff from these events have lead to land conversions from forests to shrub/grasslands that reduce all of the cooling agents talked about above. Finally, changes in plant cover also mean changes in sensible heat fluxes, which heats the surrounding areas. |
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Term
| We talked about productivity in the tropics being limited by drought. Give 2 examples of evidence we have for this based on what I showed you in class. |
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Definition
El nino events - Severity of drought matters! We’re seeing an increase in drought severity, which impacts biomass dynamics. Increased tree mortality from 2005 drought shows that the carbon sink is unstable.. (2010 and 2016 were even more severe!)
Causes of the 2005 Amazonian drought
Reduction of trade winds from the north → Northwards displacement of the ITCZ → Rainfall decrease over Amazonia
Droughts cause a decrease in NPP and an increase in atmospheric CO2, global implications as the entire precipitation regime changes
We also see an increase in fires during drought years |
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Term
| Are organisms in the tropics potentially more or less sensitive to current and predicted increase in temperatures compared to organisms in the temperate regions? Why or why not? (Should be able to discuss in terms of thermal tolerance, novel and disappearing climates and the spatial extent of similar climate in the tropics.) |
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Definition
They potentially more sensitive to temperature increase because they are not used to any change in temperature as boreal species (higher thermal tolerance due to temperature change in seasons)
Disappearing climates in the tropics will be higher and loss of suitable refugia or migration corridors for species there will make it harder for species to move to cooler areas? |
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Term
| What is the primary issue in global change that mitigation is intended to resolve? |
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Definition
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Term
| Have US emissions of CO2 increased, decreased, or stayed about the same in the past 30 years? |
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Definition
From 1990-2015 there has been a 7.9% increase in CO2 emissions. Increase in Agriculture, Energy, and decrease in industrial processes.
What is important to note is the loss of the Carbon sink, even though CO2 emissions haven’t increased all that much.
7.9% increase emissions-6.2% decrease in sink |
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Term
| What are the three most important economic sectors in terms of US greenhouse gas emissions? |
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Definition
| Transportation, Energy, and Industry |
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Term
| Be able to contrast top-down and bottom-up mitigation strategies, and provide examples of each, including levels of governance from individual to local to state to national to international. |
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Definition
Top down mitigation strategies are when government is the cause for change that improve mitigation by forcing people to change their behaviors while bottom up strategies are individual citizens and groups that perform actions forcing government to change policies and long-term strategies.
Examples:
Individual – voting/protesting/marching/being politically involved, drive less, reduce consumption, shopping locally
Local – building carpool lanes/having accessible and clean mass transit, increase green cover, divest from fossil fuel/invest in clean energy
National – reshape economy to a carbon-reduced state, incentivize broad changes to more environmentally friendly products, funding science and research
International – push more binding climate agreements, have more environmentally friendly trade agreements, basically just agreements |
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Term
| Explain what the ‘cap’ and ‘trade’ components of a cap and trade strategy are. |
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Definition
Cap=Limit
Trade=The market that allow people to buy and sell their limits
In CA, funds from state-wide cap and trade have provided funds for innovative programs to reduce GHG and has been extremely successful -- arguably most well designed on the planet! Nearly 40 countries and over 20 subnational entities developing their own cap and trade systems. eecosyetajd
Government sets gap, total divided into allowances, government distributes allowances |
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Term
| In addition to cap & trade, what are three strategies to reduce GHG emissions? Which of these is most likely to be effective in achieving desired reductions in GHGs? Will they be sufficient? |
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Definition
Alternative energy (wind, solar, nuclear (but not really-ew), geothermal, biofuels, hydroelectric)
Increase efficiency (in, like, everything: transport, energy generation, industry)
Non-CO2 GHG management
Alternative energy is most likely to be most successful. At the current moment, I don’t believe they will be sufficient, merp (sad Ryan)
Can probably argue any of these three effectively |
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Term
| What is the current status of US (national) action alternative (clean) energy development? What barriers exist to this development? |
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Definition
| Obama administration pushed national policies encouraging GHG reduction and the development of alternative energy. However, much of the policy has been rescinded by current administration. :( Many cities and other institutions have commited to pick up the slack of our national government. :) |
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Term
| What is meant by the “biofuel carbon debt” ? |
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Definition
GHG released from land conversion = carbon debt of biofuel production, and Payback period = time required for biofuels to overcome carbon debt
Ex. corn has a lot of debt, as far as how much land is used for processing versus how much GHG emissions it saves once it is processed. |
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Term
| In what type of ecosystem /land change is the biofuel debt most severe? In which type of ecosystem/ land change would the payback period for biofuel development be lowest? |
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Definition
| The most severe change would be converting peatland rainforest to palm oil plantations to create biodiesel from, with a debt of about 423 years of carbon debt. The least would be conversion of marginal cropland back to prairie grasses that are converted to ethanol with no debt incurred. The best conversions are from cropland to prairie and the worst is from rainforest to agriculture. |
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Term
| What do ‘green’ or ‘ecosystem-based’ adaptation solutions provide that ‘gray’ or engineering solutions do not? |
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Definition
Grey infrastructure are engineering projects that use concrete and steel.
Dams, water treatment plants, etc
Often lack of flexibility in adapting grey infrastructure to uncertainties, i.e. once dams are built it’s difficult (technically and economically) to adapt them to new flow conditions and changing socio-economic demands
Green infrastructure are projects that depend on plants and ecosystem services, but they may be totally constructed and artificial.
Environmental services can provide a more flexible infrastructure-like function, such as healthy watersheds purifying water or mangroves protecting the shore from extreme storms
Can help maintain grey infrastructure
Ex: adding urban green cover to prevent flooding
Green infrastructure is flexible, and can be integrated into or directly replace traditional engineering solutions while performing other valuable tasks. |
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Term
| Please review the four case studies in Lecture 22 that contrast adaptations in San Juan, Miami, Valdivia, and Phoenix. How does the star diagram illustrate the trade-offs inherent in these adaptations? |
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Definition
The overall goal is to reduce exposure, reduce sensitivity, and increase adaptive capacity. These case studies achieved results through different methods.
In San Juan, Some houses are being relocated, and the canal will turn into a nice park. To avoid gentrification, existing community has priority access. Residents led this effort- community land trust.
In Miami, Miami Beach is elevating its streets and buildings, using pumps to get rid of the tidal and rain-induced flood water. More technology oriented
In Valdivia, they opted to protect Valdivia’s wetlands, this affords protection from flooding, but reduces area available for development.
In Phoenix, they added more green spaces in water runoff areas (canals/arroyos) to slow down water during precipitation events to increase green cover and flood control/water infiltration. Dope. |
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Term
| What is the definition of geoengineering, and what are the three main ways in which geoengineering could be used to alter the current trajectory of climate change? |
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Definition
Geoengineering: Intentional modification of the Earth system to prevent further climate change. Engineering the planet
CO2 removal from the atmosphere: Ocean fertilization, Land-use practices
Solar radiation management: Albedo alteration, including reflecting solar energy or Seeding the atmosphere
Direct capture and storage of CO2 |
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Term
| What is the current level of urbanization (i.e., % of population living in cities) in the world as a whole, and in developed and developing countries? How do we expect this to change over the 21st century? Where is most human population growth happening? |
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Definition
Fifty percent of the current population
We expect 70% to live in cities by 2050
And 80-90% by 2100
Most population growth is urban and is happening in the “developing world” (not our term, from the slides) |
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Term
| What are the five major types of global change? For each of the five major types of global change discussed in class and in the Grimm et al. 2008 paper, do LOCAL or GLOBAL drivers have a greater impact on urban ecosystems TODAY? Know how these five types of global change are manifested at local and global scales (i.e., be able to give examples at these scales for each type) |
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Definition
Local environment drive changes more, think of urban environments that alter land use and cover, affect biodiversity. The finer the scale you get, the more of a direct change can occur. Everything you see on the local scale will eventually be seen in the global scale.
Five major types are land conversion, altered biogeochemistry cycles, climate change (precipchanges ), altered hydro systems, loss of biodiversity.
Land conversion
Local: building in wetlands, converting local grasslands/forests to agriculture, mountain top removal for mining
Global: cutting down a whole biome for crops, like the midwest
Biogeochemistry cycles
Local: industrial waste and fertilizer going into streams and rivers, water pollution
Global: Large fertilizer runoff into Gulf of Mexico, Cheseapeake Bay, Acid rain from too pollution, water pollution
Climate/precipitation change:
Local: fewer rain events, more extreme precipitation events, hotter and drier in some areas, disrupted weather patterns (rain when it should be snow)
Global: changes in ITCZ location in the tropics, melting ice caps and warming sea water, stronger hurricanes
Hydro systems
Local: increased impervious surfaces in local areas that causes flashier runoff, record setting rainfall events that cause massive flooding, water supply challenges (have enough/clean water)
Global: Changes in monsoon timing, higher sea levels, water scarcity
Biodiversity loss
Local: domestication of nature, introduction of invasive plant, homogenization of plant communities because of widespread appreciation of very specific plants
Global: species extinction, habitat reductions or dominance that reduce the number of niches, hybridization of plants and animals |
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Term
| For which of these types of global change do urbanization/urban systems have the greatest impact on at the global scale? How can cities be important drivers of this change, despite their small global extent? What is the global extent of urban areas? |
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Definition
Land conversion. It drives a lot of the other remaining issues. There is a huge resource demands, especially for water, think of channelizing rivers and using water for agriculture, and how this decreases biodiversity and hydraulic regimes.
Half the world's population lives in cities.
Cities represent small land area with an out of proportion land and ecological impacts. |
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Term
| What are two major challenges associated with urban infrastructure, thinking about the future under climate and other global changes? |
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Definition
Infrastructure is a fundamental component of urban social-ecological systems (SETS) that provide protection against hazards and additional benefits. However they impact air, water, soil quality, and increase impervious surface cover (i.e. alter microclimates).
Much infrastructure is aging and in poor condition - Natural events can cause immense damage (think thawing permafrost, earthquakes, flooding, etc.)
Inflexible, rigid design - do not hold up against natural events (soil subsidence)
Designs based on probabilities that do not take future climate trends into account - built right in flood planes, in areas without water, flood prone and fire prone
Decisions about infrastructure have social and ecological impacts - urban heat island, loss of impervious surfaces
Expensive and inaccessible for rapidly growing cities in poor condition -
Urban sprawl - housing insecurity has led to many tent cities/shacktown surrounding major cities, these are especially vulnerable to the elements (fire prone, flood prone, heat exhaust, pollution) |
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Term
| Explain how the vectors of pollutant movement affect the scale of impact of urban pollution. |
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Definition
Soil has the least amount of movement of pollutants and have the longest residence times (example of lead in New Orleans soils taking forever to wash out, during katrina)
Water has a moderate amount of movement and takes a lot of pollution because of waste runoff from cities and industrial areas
Air has the most amount and quickest movement and mixing |
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Term
| What is a point source? a non-point source? Be able to give two examples of each. |
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Definition
Point source - Any pollution coming a very specific area that does not change over time. For example: wastewater, effluent, animal feed lot runoff, storm sewer outfalls from large population centers
Non-point source - diffused and more dispersed pollution, like agricultural runoff and atmospheric deposition |
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Term
| Name the type of pollutant that is unique to urban systems. Why are problems associated with these pollutants getting worse? |
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Definition
Pollutants such as medication and personal care products in water systems are are also unique to cities.
Heavy metals is higher in urban areas, especially with lead. Has a huge legacy effects and environmental justice issues.
Problems is their ability to live in soils less mobile constituents such as metals like Pb, Zn, Cd usually elevated in urban soils. |
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Term
| What is the urban heat island? What are 5 consequences of higher than average temperatures? What are two factors that make urban heat island temperatures higher? |
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Definition
The urban heat island effect is the phenomenon where reductions in vegetative cover, increases in low albedo surfaces that absorb more radiation, and high heat production from more energy use leads to higher average temperatures in cities than in the surrounding area.
Five (plus) consequences of higher average temperature include:
1. Increased energy loads
2. Structural failures in energy infrastructure
3. Raise energy bills
4. Increase power outages
5. Increase fatal exposure to heat
6. Limit medical and social services
7. Reduce quality of life
8. Food price volatility
9. Urban drinking water |
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Term
| What is the urbanization drives homogenization hypothesis? What is an example? |
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Definition
Hypothesis: Within urbanizing regions, landscape alteration and management result in a relative homogenization of form and function of urban land cover across climate zones.
Ex. Some evidence in plant communities (class example) - Lawns across US cities have very similar plant communities compared to their respective surrounding lands. Implication of homogenization is loss of ecosystem structure and function within urban areas. |
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Term
| Give at least 3 reasons why freshwater biomes are vulnerable to climate change. |
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Definition
1.Habitat fragmentation, limited in size and location, organisms cannot disperse or migrate
2.Water temperature and availability are climate dependent (think precipitation)
3.Freshwater systems are already exposed to anthropogenic stressors like pollution, degradation, encrouachment, and nutrient loading, fishing/harvesting, draining, channelization |
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Term
| How specifically will an increase in temperature alone affect the physical habitat occupied by freshwater species? Be able to discuss 3 examples. |
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Definition
An increase in temperature increases metabolic rates of higher-level consumers, meaning an increase in consumption of lower trophic levels.
An increase in temperature causes a decline in dissolved oxygen levels in the water, which either means fewer organisms can live at that level in the water. In response, organisms that can swim to lower levels with more oxygen will have to do so or organisms die of hypoxia.
An increase in temperature causes fewer strata to form in lakes, which reduces areas that unique niches can occur, thus squeezing out species that cannot compete together for limited resources.
An increase in temperature reduces the mixing potential in lakes when turnover occurs that helps move nutrients further up the water column twice a year. This is especially important for primary producers that need key nutrients to be able to grow. |
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Term
| How will potential changes in the hydrological regime alone modify habitat for freshwater species? Be specific in terms of talking about at least 3 changes in hydrological regimes. |
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Definition
Change in timing of hydraulic inputs - i.e. snowmelt occurring earlier/later than expected, or changes in monsoon season
Flow rate - slower flow rate could impact water quality, faster flow rate could wash away nutrients faster than organisms can uptake
Volume of water - too much water could introduce more pollutants to system, wash away habitat and nutrients, decrease water volume could lose habitat and organisms
Wet/dry - similar to volume
Variability in the quantity and timing of precipitation → magnitude, frequency, duration, and timing of runoff |
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Term
| What options do species have to respond to these changes? |
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Definition
acclimate
adapting?
migrating? (but really the majority of species will not be able to do this, freshwater species)
Perish |
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Term
| How will the depth of the lake affect the potential impact of increased temperature? |
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Definition
| In more shallow lakes, there will be insufficient oxygen in deeper, cool water to support large game fish, could lead to cascade in which key predatory fish species are eliminated, smaller fish increase in abundance and reduce zooplankton populations and algae proliferate and decrease water clarity |
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Term
| Which wetlands are created by precipitation inputs alone vs. fed by nearby streams/rivers/lakes? Does this influence their vulnerability and why? |
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Definition
Bogs- fed by precipitation
Marshes- fed by rivers, lake, ocean coast etc.
These are the most vulnerable, too much flooding can cause a loss of habitat
Swamp - fed by flooding and draining or nearby water sources
Fen - fed by small streams and groundwater
All of these depend on outside water system therefore all of them are vulnerable to changes in their dependent water system. |
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Term
| How do human activities harm freshwater ecosystems? Be ready to discuss at least 3 examples. |
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Definition
LULLC has led to a drastic increase in impervious surfaces that lead to flashier runoff and greater sediment loss because of that. Also leads to lower levels of water with higher peaks and faster runoff rates when precipitation events do occur.
Increase in pollution that inevitably runs off into streams, rivers, and lakes. This pollution causes severe problems to animals, especially amphibians.
Overfishing in these systems has fundamentally changed the habitat. When overfishing removes too many game fish, the stocking of non-native species also causes great harm to the system.
Increased temperatures and/or the removal of vegetation that causes increased radiation on streams has drastically harmed species that are adapted to very specific conditions. |
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Term
| Be ready to discuss 3 policy changes that could reduce these impacts on freshwater ecocsytems. |
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Definition
Policy to prevent urban development or other modifications of wetlands
We have built on top of many wetlands and drained them for agricultural purposes. This has caused many cities to be flood prone, and preventing development will add flood protection to many areas.
Policy to reduce pollution runoff (agriculture or urban)
Agricultural runoff and urban waste (scat, chemicals, etc.) often end up in our water ways, and can have detrimental cascading effects (think plant die off, species die off, dead zones)
Policy to restore wetlands (be careful defining what success is)
Lots of money in restoration, could have flood protection benefits and carbon storage benefits.
Policy to conserve and protect current wetlands
As is the case in tropical forests, the carbon benefit is much higher when we conserve areas vs restore |
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Term
| How did the restoration Tomer describe in the NJ Meadowlands affect carbon balance of the system? From a carbon perspective, was this restoration successful, why or why not? |
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Definition
The results show that the restoration caused a lower C uptake/higher C release? by the plants in the restored area vs the area with the invasive species (because this species has a high C sequestration and does well in polluted environments) But, what they did with disturbing the soil in the restoration, may be what is influencing the higher C release in the restoration area,. So maybe it is too soon to tell which species is releasing more carbon into the system.
With the information we have now, from a carbon perspective, we could say that the restoration was not successful. |
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Term
| How specifically does the biological pump work in the ocean? What is pumped down to the bottom of the ocean? Why is it so important to global carbon cycling and climate? |
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Definition
| Kevin’s answer: The biological pump describes the movement of carbon from atmospheric CO2 to CO2 captured by aquatic plants and eventually pushed down to lower levels of the ocean as detritus. Carbon in the form of sugars of some form or another. It captures and sequesters millions of tons of carbon every year, some of which is moved back to the earth's mantle over millions of year. It is now the best way that Earth can sequester carbon for eons. |
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Term
| Be able to list all of the primary producers in the ocean. Which ones are the most important? |
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Definition
Phytoplankton - most important
Calcareous : coccoliths
Siliceous: diatoms
Microbes: cyanobacteria and N fixers
Macrophytes: large plants
The larger they are the less efficient they are at recycling nutrients |
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Term
| How do global rates of NPP in ocean compare to that on land? What are primary differences between primary producers on land and in the ocean? |
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Definition
| Global NPP in oceans are slightly lower than rates on land, with oceans taking in about 50 GtC/year while land takes in about 55 GtC/year. Even though the rates are comparable, the total biomass of primary producers is much less in oceans than on land, with only about 2 GtC of primary producers in oceans versus 70 GtC on land. The main differences that cause this are the residence/life time of the primary producers and how the dead material ends up getting disposed of in the systems. Ocean primary producers are mostly algae and diatoms, which have fast turnover compared to trees (could not find how old algae can get online). When algae does die, it sinks to the bottom of the ocean, thus trapping that carbon and helping form the biological pump. On land, primary producers live for tens to thousands of years at times, but will be decomposed when they die/drop leaves and needles and carbon released back into the atmosphere. |
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Term
| What are the primary requirements for NPP in the ocean? |
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Definition
Dissolved carbon (typically available)
Calcium (rapidly assimilated to make shells and such)
N, P, Fe, Si (scarce in surface waters… dependent on mixing to get these nutrients!)
Light! (scarce below 80 m, in addition to seasonal limits)
Often the most limiting factor is either light or nutrients, the ocean is co-limited in that sense depending on where in the ocean you are talking about. |
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Term
| How has phyotoplankton NPP been changing over time? How has zooplankton NPP been changing? What do the differences between them suggest? |
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Definition
Over time with increasing temperatures, NPP has declined. because of water stratification there is less nutrient mixing (Limits nutrient fluxes into the euphotic zone) and less possibility for phytoplankton to bloom. Zooplankton biomass has declined and so NPP has decreased too even more than phytoplankton’s biomass globally?
Tropics limiting factor: nutrients. because there is less mixing there is lower nutrient supply --> less plankton near surface
Higher latitudes limiting factor: light. Less mixing but Increase in plankton in illuminated areas |
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Term
| Define thermal stratification, specifically how it occurs, it is altered by climate change and the consequences for marine life. |
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Definition
| The separation of water into different layers based on temperature. It occurs because the density of water changes as its temperature changes. The stratification causes layering of oxygen levels, nutrients, and light which changes which creatures can survive in various levels. |
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Term
| How have oxygen concentrations been changing over time in the ocean and why? Specifically what role has increased temperature played? |
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Definition
O2 concentration has decreased because of warming (thermal stratification). This is because less O2 is dissolved in warm water. Warmer conditions can cause an increase in respiration and cause O2 to get used up quicker.
This can lead to eutrophication, causing algal blooms. |
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Term
| What is the physical evidence for climate change having any impact on oceans? You should be able to discuss at least 4 different changes we are seeing. |
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Definition
There has been a sharp drop in phytoplankton levels over the past 110 years that has averaged about 1% decline per year. This is likely because of warming ocean temperatures leads to less ocean mixing that occurs at higher levels in the ocean (meaning fewer nutrients are brought up from the ocean bottom).
Decreases in dissolved oxygen content that occur from warming ocean temperatures (that cannot hold as much oxygen in the water). When combined with nutrient runoff entering oceans to cause algal blooms, hypoxic conditions can cause dead zones that kill off most life in that ocean area.
Coral bleaching has been occurring across all oceans that harbor coral life because of increased ocean temperatures and pollution. The changes in environment stresses the coral to the point where symbiotic algae leave and cause the coral to lose their primary source of food. The loss of coral reefs mean the loss of habitat for small and young fish, which have been detrimentally affected by the habitat change as well
Shifts in species habitat range, distribution, and abundance for mobile ocean organisms that has likely occurred because of changes in ocean temperature. This had lead to a high likelihood of permanent changes of northern shifts for northern hemisphere fish.
Ocean acidification has lead to a myriad of problems for shelled organisms because there is less calcium carbonate from which to construct protective shells, which reduces calcification rates. For non-shelled organisms, the decrease in calcium carbonate/pH has led to issues that include reduced smell, increased noise, reduced metabolic activity (and even death), and poor larval development.
A drastic decline in ocean biodiversity that has occurred from all of these problems (acidification, dissolved oxygen, ocean temperature that lead to the first 5 problems that cause declining biodiversity). |
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Term
| What are the changes we are seeing in terms of northward shifts of organisms in the ocean? |
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Definition
| Ocean warming, acidification, and deoxygenation are leading to changes in productivity, recruitment, and survivorship across the oceans. Additionally, we are beginning to observe active movements of species as they track their preferred temperature conditions. This is resulting in populations moving northward or deeper in water to find their ideal, cooler temperatures. These changes impact the distribution and availability of many commercially and recreationally valuable fish and invertebrates. This interacts with fishery management decisions, from seasonal and spatial closures to annual quota setting, allocations, and fish stock rebuilding plans. |
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Term
| Why do some people say jellyfish are taking over the oceans? What abiotic factor are they responding to? |
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Definition
| In the past few years, jellyfish blooms have been more common affecting different human activities. Jellyfish are very tolerant of low O2 conditions. With climate change, oceans are experiencing low O2 levels and jellyfish seem to be very resilient to it. |
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Term
| Why does ocean acidification go hand in hand with elevated CO2? What is evidence that ocean acidification is occurring and be able to discuss at least 3 consequences of this for marine life. |
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Definition
Increased CO2 levels pushes more dissolved oxygen into the ocean, and when CO2 is dissolved in water, it reacts with water to become carbonic acid, which further dissociates into 2 protons and a carbonate ion
Kevin’s attempt: More atmospheric CO2 means oceans absorb more CO2, which dissociates and forms carbonic acid with water. This then reacts with CaCO3 or stays as an acid to decrease pH. Evidence is decreased availability of CaCO3 and lower average pH in the oceans. This causes a decrease in shell production from crustaceans, blood acidosis that can cause asphyxiation, and poor larval development of invertebrates. |
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